The Interpretation of Seismogenic Fault of the Maduo Mw 7.3 Earthquake, Qinghai Based on Remote Sensing Images-A Branch of the East Kunlun Fault System

On May 22, 2021, a Mw 7.3 earthquake occurred in Maduo County, Qinghai Province with the epicenter of 34.59 degrees N, 98.34 degrees E. The distribution of aftershocks and surface ruptures suggested that the seismogenic structure might be the Jiangcuo fault (JF), <70 km south of East Kunlun fault (EKLF). Due to the high altitude and sparse human habitats, there are very few researches on the Jiangcuo fault, which makes us know little about the deformation features and even the geometry of Jiangcuo fault. In this study, we used the high-resolution pre-earthquake satellite images to interpret the spatial distribution and geometry of the Jiangcuo fault. Our results show that the Jiangcuo fault strikes nearly east, extending 180-km-long from Eling Lake to east of Changmahe Town. Based on the geometric features, the Jiangcuo fault could be divided into three segments characterized as the linear structures, fault valleys, scarps and systematic offset of channels. The boundary between Bayan Har Block and Qaidam Block is presented as a wide deformation zone named of Kunlun belt that is composed of East Kunlun fault and several branch faults around Anemaqen Mountain. Geometric analysis and deep lithosphere structure around Maduo County suggest that the Jiangcuo fault should be one of branch of East Kunlun fault at south, where the Kunlun fault developed as a giant flower structure. In addition, the seismic hazards potential of Jiangcuo fault should be given enough attention in the future, because west of the Jiangcuo fault, there is a rupture gap between the co-seismic surface ruptures of the 2001 Kunlun, 2021 Maduo and 1937 Huashixia Earthquakes.